1. Field of the Invention
The present invention relates to an image input/output apparatus and, more particularly, to an image input/output apparatus which can attain two-dimensional image input (reading) and output (display) operations.
2. Related Background Art
As a conventional portable image input/output apparatus, a combination of an image input device such as a one-dimensional hand scanner, a one-dimensional image reader, or the like, and an image output device such as a liquid crystal display is popularly used. However, in such a portable image input/output apparatus, a user who operates a one-dimensional image input unit as an image input device must manually move the image input unit along an original, or an original must be mechanically scanned relative to the image input unit.
However, when a manual scanning operation is performed, the scanning speed of the image input unit relative to the original is often improper or nonuniform, and a reading error often occurs, resulting in poor operability. When a mechanical scanning operation is performed, although a proper and constant scanning speed can be obtained, the scanning device becomes large in size, and the consumption power increases. In either case, since the scanner is required in addition to the display device, problems associated with a complicated structure and high cost as a portable apparatus, and a problem associated with portability remain unsolved.
Under these circumstances, a method of performing an original reading operation and an image display operation by utilizing a two-dimensional image input device and an image output device such as a two-dimensional liquid crystal display has been proposed.
For example, Japanese Laid-Open Patent Application No. 4-282609 describes input/output integrated information processing equipment, in which an image input unit having an image sensor formed on a first transparent substrate, and an image output unit having a second transparent substrate formed with TFTs and transparent driving electrodes, color filters, and a liquid crystal are integrally stacked. This patent application also describes input of desired information by utilizing reflection of light at a pen tip, or using a pen having a light source in its pen tip.
Japanese Laid-Open Patent Application No. 5-244346 describes an image processing apparatus in which a display device constituted by a liquid crystal display as an image output unit and a backlight is arranged on the rear surface of an image input unit comprising an amorphous silicon array two-dimensional optical sensor as reading means, and light emitted by the backlight is used in an image reading operation.
In addition, since each of these apparatuses has a single image input/output surface, as shown in FIG. 1, an apparatus 30 must be reversed to face down and placed on an original 20 to read the original 20. Furthermore, in order to display the read image and visually observe the displayed image, the apparatus 30 must be reversed to face up, so that an image input/output surface 110 can be visually observed.
Even when an original reading operation is performed by reversing an original to face down and placing it on the image input/output surface of the apparatus without reversing the apparatus to face down, an operator must remove the read original from the surface of the apparatus so as to display the read image and visually observe the displayed image.
In this manner, when a single surface serves as both image input and output surfaces, the entire image input apparatus must be reversed to face up or down every time image input and output operations are performed.
When a region to be read of, e.g., an original is equal to or almost equal to the input region of the image input unit, since the entire apparatus is reversed to face down, it is difficult to set the region to be read to fall within the input region. As a result, the input and display operations must be alternately repeated to confirm the input image.
Furthermore, when a region to be read of, e.g., an original has a low contrast or a low chromatic contrast, confirmation of the read information must often be required similarly. In this case, the operation for reversing the entire apparatus must also be repeated until an optimal input is attained.